abstract: The Philadelphia chromosome in humans, is on oncogenic translocation between chromosomes 9 and 22 that gives rise to the fusion protein BCR-Abl. This protein is constitutively active resulting in rapid and uncontrolled cell growth in affected cells. The BCR-Abl protein is the hallmark feature of chronic myeloid leukemia (CML) and is seen in Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) cases. Currently, the first line of treatment is the Abl specific inhibitor Imatinib. Some patients will, however, develop resistance to Imatinib. Research has shown how transformation of progenitor B cells with v-Abl, an oncogene expressed by the Abelson murine leukemia virus, causes rapid proliferation, prevents further differentiation and produces a potentially malignant transformation. We have used progenitor B cells transformed with a temperature-sensitive form of the v-Abl protein that allows us to inactivate or re-activate v-Abl by shifting the incubation temperature. We are trying to use this line as a model to study both the progression from pre-malignancy to malignancy in CML and Imatinib resistance in Ph+ ALL and CML. These progenitor B cells, once v-Abl is reactivated, in most cases, will not return to their natural cell cycle. In this they resemble Ph+ ALL and CML under Imatinib treatment. With some manipulation these cells can break this prolonged G1 arrested phenotype and become a malignant cell line and resistant to Imatinib treatment. Cellular senescence can be a complicated process requiring inter-play between a variety of players. It serves as an alternate option to apoptosis, in that the cell loses proliferative potential, but does not die. Treatment with some cancer therapeutics will induce senescence in some cancers. Such is the case with Imatinib treatment of CML and Ph+ ALL. By using the S9 cell line we have been able to explore the possible routes for breaking of prolonged G1 arrest in these Ph+ leukemias. We inhibited the DNA damage sensor protein ataxia telangiectasia mutated (ATM) and found that prolonged G1 arrest in our S9 cells was broken. While previous research has suggested that the DNA damage sensor protein ataxia-telangiectasia mutated (ATM) has little impact in CML, our research indicates that ATM may play a role in either senescence induction or release. / Dissertation/Thesis / M.S. Microbiology 2011

付記する学位プログラム名: 京都大学卓越大学院プログラム「メディカルイノベーション大学院プログラム」 / 京都大学 / 新制・課程博士 / 博士(人間健康科学) / 甲第25213号 / 人健博第119号 / 新制||人健||8(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 錦織 桃子, 教授 岡 昌吾, 教授 羽賀 博典 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

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CXCR4, récepteur de la chimiokine SDF-1 (stromal cell-derived factor 1) joue un rôle capital dans l’hématopoïèse normale mais aussi dans la biologie de la cellule leucémique. Ce récepteur est exprimé à la surface des blastes et participe à « l’ancrage » de la cellule souche leucémique (CSL) au sein de la niche médullaire. Les interactions de la CSL avec le micro-environnement sont source de signaux de survie et de résistance à l’apoptose. La première partie de ce travail correspond à deux analyses en cytométrie en flux de l’expression de CXCR4 et de molécules d’adhérence sur des échantillons diagnostiques de LAM (leucémie aiguë myéloïde). Ce travail confirme la valeur pronostique péjorative de l’expression de CXCR4 et propose un modèle de stratification pronostique des patients, en fonction de leur phénotype d’adhérence. La deuxième partie s’intéresse à l’identification de potentielles cibles thérapeutiques dans un modèle de LAL à chromosome Philadelphie, pathologie au pronostic sombre malgré les progrès thérapeutiques liés aux ITK (inhibiteurs de tyrosine kinase). L’inhibition de CXCR4 par l’AMD3100 permet de potentialiser l’efficacité de l’aracytine et du dasatinib dans un modèle de co-culture stromale avec la lignée SUPB15. Une deuxième piste de ciblage thérapeutique de la LAL Phi+ est l’inhibition de la protéine chaperone HSP90. Une expression forte de HSP90 (dans les LAL Phi+ par rapport aux LAL Phi-) s’associe à une plus grande cytotoxicité du 17-AAG. En conclusion, CXCR4 est un récepteur clé de la cellule leucémique. L’étude de son niveau d’expression permet des stratifications pronostiques des patients et son blocage en fait une cible thérapeutique prometteuse / CXCR4, receptor of the chemokine SDF-1 (stromal cell-derived factor 1) plays a major role in the normal hematopoiesis but also in the biology of the leukaemic cell. This receptor is expressed on the surface of blasts and is a key molecule in "the anchoring" of the leukaemic stem cell (LSC) within the bone marrow niche. The interactions of the LSC with the bone marrow microenvironment promote survival signals and drug resistance. The first part of this work consists of two flow cytometry analyses of CXCR4 and adhesion molecules expression in patients with AML (acute myeloid leukaemia) at diagnosis. The results confirm that CXCR4 expression is associated with poor prognosis and this work proposes to stratify patients, according to their adhesive phenotype, in order to establish risk-adapted strategies. The second part deals with the identification of potential therapeutic targets in a model of ALL with chromosome Philadelphia. Despite therapeutic improvements with the ITK (tyrosine kinase inhibitors) era, long term survival remains poor. The inhibition of CXCR4 by the AMD3100 enhances the sensitivity of SUPB15 cell line to cytarabine and dasatinib therapy in a model of stromal co-culture. A second way of therapeutic targeting of the ALL Phi + is the inhibition of the heat-shock protein HSP90. High percentage of HSP90-positive cells (in Ph+ ALL samples) is associated with high sensitivity to 17-AAG. In conclusion, CXCR4 appears as a key receptor of the leukaemic cell. The analysis of its level of expression allows prognostic stratifications and its blockade represents a promising therapeutic target

Orientadores: Katia Borgia Barbosa Pagnano, Afonso Celso Vigorito / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-14T18:14:56Z (GMT). No. of bitstreams: 1 Machado_MelissaPereira_M.pdf: 1144638 bytes, checksum: c55a80d3cce151782b16b741b0f21149 (MD5) Previous issue date: 2009 / Resumo: A leucemia mieloide crônica (LMC) e uma desordem mieloproliferativa caracterizada pela presença do cromossomo Philadelphia (Ph), resultado da fusão do gene abl e do gene bcr cujo produto e uma proteína de atividade de tirosina quinase, inibida pelo mesilato de imatinibe. O imatinibe e hoje o tratamento de primeira linha da LMC e o monitoramento molecular dos transcritos BCR-ABL e fundamental no acompanhamento dos pacientes e na detecção precoce da perda de resposta ao tratamento. O objetivo deste trabalho foi realizar a padronização do método de PCR quantitativo (RQPCR) para o monitoramento molecular dos transcritos BCR-ABL de pacientes com LMC em tratamento com imatinibe. Foram coletadas amostras de sangue periferico de pacientes com LMC para RQ-PCR ao diagnostico e a cada três meses apos o tratamento com imatinibe. Foi utilizado o método Taqman. Como gene controle foi utilizado o ABL. Foi criada uma curva standard com diluições de 108 a 103 de um plasmideo com os transcritos b3a2 e b2a2 e com ABL. As quantificações foram feitas em duplicatas, assim como a curva standard. O threshold utilizado foi de 0,05 e a eficiência foi determinada em 99%. Os resultados foram reportados como uma relação entre BCR-ABL/ABL. Para o valor de referencia basal do laboratório foram analisadas 30 amostras de pacientes ao diagnostico, e calculada a mediana, sendo esse valor 83,66%. Resposta molecular maior (RMM) foi definida como redução dos transcritos BCR-ABL em 3 log a partir do valor basal do laboratório. Os valores foram ajustados a escala internacional, usando-se um fator de conversão de 1.19. Apos a padronização do método, foram avaliados 60 pacientes com LMC, cujas amostras foram coletadas ao diagnostico e a cada 3 meses. Respostas hematológica, citogenetica maior e citogenetica completa foram obtidas em 57 (95%), 45 (75%) e 38 (63%) dos pacientes, respectivamente. Vinte e quatro de 60 pacientes atingiram a RMM (40%), numa mediana de 8,5 meses. A sobrevida global foi superior nos pacientes com RCC (100%) vs pacientes sem RCC (77%) em 48 meses. Pacientes com RCC e com RMM tiveram uma sobrevida livre de eventos superior em relação aos pacientes que não atingiram os dois tipos de reposta (100% vs 60% respectivamente) (p= 0.007). Em resumo, neste estudo demonstramos o impacto prognostico em atingir RCC e RMM e também a importância do acompanhamento molecular nos pacientes com LMC. / Abstract: Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the presence of Philadelphia chromosome (Ph), the result of bcr and abl gene fusion, which product is a protein with kinase activity, inhibited by imatinib. Imatinib is currently the first-line treatment of CML and molecular monitoring of BCRABL transcripts is essential in monitoring of patients and for the early detection of loss of response to treatment. The aim of this study was to standardize quantitative PCR (RQ-PCR) method for molecular monitoring of BCR-ABL transcripts in patients with CML treated with imatinib. Peripheral blood samples from chronic phase patients were collected for RQ-PCR at diagnosis and every three months after treatment with imatinib. Taqman method was used for RQ-PCR. A standard curve with dilutions of 108 to 103 of a plasmid with the b3a2 and b2a2 transcripts and ABL gene, used as the control gene, was constructed. The runs were made in duplicates. The threshold used was 0.05 and the efficiency was determined as 99%. The results were reported as a BCR-ABL/ABL ratio (%). For the reference value of the baseline of the laboratory 30 samples from patients at diagnosis were quantified and the median value calculated was 83.66%. Major molecular response (MMR) was considered a three log reduction from the baseline value. MMR values were adjusted to international scale, using a conversion factor of 1.19. After standardization, BCR-ABL levels of 60 CML patients in chronic phase treated with imatinib were measured at diagnosis and then every three months. Hematological, major cytogenetic and complete cytogenetic responses were achieved in 57 (95%), 45 (75%) and 38 (63%) patients, respectively. Twenty-four out of 60 patients achieved a MMR (40%), in a median time of 8.5 months. Overall survival was superior for patients with CCR (100%) versus patients with no CCR (77%) (p= 0.01) in 48 months. Patients with CCR and with MMR had a superior event free-survival (EFS) in comparison with patients with CCR and no MMR (p= 0.007). In conclusion, we could demonstrate the prognostic impact of achieving CCR and a major molecular response and also the importance of molecular monitoring in the follow-up of CML patients. / Mestrado / Ciencias Medicas / Mestre em Clinica Medica

The human Philadelphia chromosome (Ph) arises from a translocation between chromosomes 9 and 22 [t(9;22)(q34;q11)]. The resulting chimeric BCR-ABLoncogene encodes a constitutively activated, oncogenic tyrosine kinase that induces chronic myeloid leukemia (CML) and B-cell acute lymphoblastic leukemia (B-ALL). The BCR-ABL tyrosine kinase inhibitor (TKI), imatinib mesylate, induces a complete hematologic and cytogenetic response in the majority of CML patients, but is unable to completely eradicate BCR-ABL–expressing leukemic cells, suggesting that leukemia stem cells are not eliminated. Over time, patients frequently become drug resistant and develop progressive disease despite continued treatment. Two major reasons cause the imatinib resistance. The first one is the BCR-ABL kinase domain mutations which inhibit the interaction of BCR-ABL kinase domain with imatinib; the second one is the residual leukemia stem cells (LSCs) in the patients who are administrated with imatinib. To overcome these two major obstacles in CML treatment, new strategies need further investigation. As detailed in Chapter II, we evaluated the therapeutic effect of Hsp90 inhibition by using a novel water-soluble Hsp90 inhibitor, IPI-504, in our BCR-ABL retroviral transplantation mouse model. We found that BCR-ABL mutants relied more on the HSP90 function than WT BCR-ABL in CML. More interestingly, inhibition of HSP90 in CML leukemia stem cells with IPI-504 significantly decreases the survival and proliferation of CML leukemia stem cells in vitro and in vivo. Consistent with these findings, IPI-504 treatment achieved significant prolonged survival of CML and B-ALL mice. IPI-504 represents a novel therapeutic approach whereby inhibition of Hsp90 in CML patients and Ph+ ALL may significantly advance efforts to develop a cure for these diseases. The rationale underlying the use of IPI-504 for kinase inhibitor–resistant CML has implications for other cancers that display oncogene addiction to kinases that are Hsp90 client proteins. Although we proved that inhibition of Hsp90 could restrain LSCs in vitro and in vivo, it is still unclear how to define specific targets in LSCs and eradicate LSCs. In Chapter III, we took advantage of our CML mouse model and compared the global gene expression signature between normal HSCs and LSCs to identify the downregulation of Pten in CML LSCs. CML develops faster when Pten is deleted in Ptenfl/fl mice. On the other hand, Pten overexpression significantly delays the CML development and impairs leukemia stem cell function. mTOR is a major downstream of Pten-Akt pathway and it is always activated or overepxressed when Pten is mutated or deleted in human cancers. In our study, we found that inhibition of mTOR by rapamycin inhibited proliferation and induced apoptosis of LSCs. Notably, our study also confirmed a recent clinical report that Pten has been downregulated in human CML patient LSCs. In summary, our results proved the tumor suppressor role of Pten in CML mouse model. Although the mechanisms of Pten in leukemia stem cells still need further study, Pten and its downstream, such as Akt and mTOR, should be more attractive in LSCs study.

O STI (imatinib, Glivec) é um inibidor da tirosina quinase BCR-ABL, responsável pela patogênese da leucemia mielóide crônica (LMC). Um total de 110 pacientes com LMC na fase crônica (FC) que falharam ou foram intolerantes ao tratamento com interferon, fase acelerada (FA) e crise blástica (CB) foram tratados com imatinibe entre dezembro de 2000 e setembro de 2003. Resposta hematológica completa e resposta citogenética maior foram observadas em 95,9% e 69,4% respectivamente em pacientes em FC e 93,2% e 36,4% em FA. Apenas 2 pacientes na CB estão vivos. O imatinib foi bem tolerado com altas taxas de resposta. / STI571 (Imatinib, Glevec) is an inhibitor of the Bcr-Abl tyrosine kinase that is central to the pathogenesis of chronic myelogenous leukemia (CML). A total of 110 patients with CML chronic phase (CP) who failed or were intolerant to interferon, accelerated phase (AP) and blastic crisis (BC) were treated with imatinib from December 2000 until September 2003. Complete hematologic response and major cytogenetic response were observed in 95,9% and 69,4% respectively of patients in CP and 93,2% and 36,4% in AP. Only 2 patients are alive in BC. Imatinib is well tolerated with high rates of response

O STI (imatinib, Glivec) é um inibidor da tirosina quinase BCR-ABL, responsável pela patogênese da leucemia mielóide crônica (LMC). Um total de 110 pacientes com LMC na fase crônica (FC) que falharam ou foram intolerantes ao tratamento com interferon, fase acelerada (FA) e crise blástica (CB) foram tratados com imatinibe entre dezembro de 2000 e setembro de 2003. Resposta hematológica completa e resposta citogenética maior foram observadas em 95,9% e 69,4% respectivamente em pacientes em FC e 93,2% e 36,4% em FA. Apenas 2 pacientes na CB estão vivos. O imatinib foi bem tolerado com altas taxas de resposta. / STI571 (Imatinib, Glevec) is an inhibitor of the Bcr-Abl tyrosine kinase that is central to the pathogenesis of chronic myelogenous leukemia (CML). A total of 110 patients with CML chronic phase (CP) who failed or were intolerant to interferon, accelerated phase (AP) and blastic crisis (BC) were treated with imatinib from December 2000 until September 2003. Complete hematologic response and major cytogenetic response were observed in 95,9% and 69,4% respectively of patients in CP and 93,2% and 36,4% in AP. Only 2 patients are alive in BC. Imatinib is well tolerated with high rates of response